Modular jacks are used in a variety of applications, such as telephone jacks for interfacing a modular telephone plug with a printed circuit board. Most modular jacks are fairly conventional in that they include a housing molded from an insulating material, with a plug receiving cavity opening at a front mating face of the housing, and with a row of cantilevered spring contact arms anchored in the housing and projecting into the cavity such that the contact arms are resiliently engaged by respective contacts of a complementary plug when it is inserted through the opening into the cavity. In many electronic environments, the jack typically is mounted to a printed circuit board, panel or the like, with the spring contact arms being portions of terminals which are electrically connected to conductive areas or circuit traces on the circuit board or panel.
In some applications, it is necessary to shield the interfacing circuits to avoid generating electromagnetic interference, and/or to avoid being impacted by ambient electromagnetic interference. For instance, the cables leading to the plug may include an electrically conductive shield, such as a braid or a foil, extending around the conductors of the cable. The plug itself will include an electrically conductive shield extending thereabout and in electrical contact with the shield of the cable. The jack, itself, will include its own shield which will be grounded to the board on which the jack is mounted. The jack shield typically is mounted on the outside or on the inside of the housing, and solder tails or other board contact means are provided for connecting the shield to grounds on the printed circuit board.
In other modular jack applications, it is necessary to detect the introduction of a plug into the cavity of the modular jack. Heretofore, such detection often has been accomplished by using one of the resilient contact arms or terminals of the modular jack. However, with such a system, that particular terminal is not available for any other use.
In still further applications, the modular jack may be coupled to a "shared line", whereby an additional, normally closed, circuit is required so that the circuit can be opened by the insertion of a plug into the jack to prevent use of the shared line by other jack and plug interfaces. Heretofore, such systems have required additional jack components, integrally molded cams or the like for effecting opening or breaking of the normally closed circuit.
This invention is directed to providing a modular shielded jack system which performs all of the above functions for the various stated applications in a very simply manner, without losing any of the jack circuits (i.e. to detect insertion of a plug) and without requiring extra components, cams and the like on the jack housing for opening normally closed circuits.